Rainbird 1800 Series Pop-Up Spray Head with Pressure Regulator Without Nozzle, 12" 12 in. 1800-series pop-up sprinkler with Rain Bird Flow Optimizer Technology Patented PRS pressure regulator built into the stem - No parts to be installed at the site Saves time and money - Maintains constant outlet pressure at 30psi (2.1 bar) Ensures maximum nozzle performance, even with varying inlet pressures Maintains constant pressure regardless of nozzles used